The U.S. Department of Justice has demanded documents related to the transmission used in about 2 million of Ford Motor Co.'s Fiesta and Focus vehicles sold throughout this decade, the Detroit Free Press reported on Wednesday.

The newspaper obtained a subpoena issued in April in Case No. 126 before a District of Columbia grand jury requesting "all documents, communications and electronically stored information" relating to the company's actions involving the DPS6 PowerShift transmission dating back to 2010, the report said.

A Ford spokesman told Reuters that it has cooperated with the National Highway Traffic Safety Administration as to DPS6-related issues beginning in 2014.

The automaker has taken a number of actions to enhance transmission performance, including extending warranties for customers from between five years/60,000 miles and seven years/100,000 miles, the spokesman added.

Ford has been grappling with litigation stemming from the faulty transmissions for several years. Former CEO Mark Fields earlier this year was ordered to testify in at least one of the cases, as Automotive Newsreported in July.